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Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xi, 157 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 96).

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2006. / Producing high quality end products, rather than focusing on volume production, is slowly but surely becoming the main driving force in the wood processing industry of South Africa. Drying defects such as surface checks and discolouration by yellow stain and kiln brown stain are major factors in softwood timber downgrades when selecting furniture grade timber. Previous efforts to control these defects have focused on schedule adaptation, but as the industry is still mainly concerned with volume production, and because of the varying lumber price, longer schedules to control these drying defects have not yet been that attractive for the larger sawmills. In ongoing research in this laboratory, a dip treatment of freshly sawn softwood boards in an aqueous solution containing a surfactant called sodium lauryl sulphate (SLS) was used to try to influence the mechanism involved in the development of these stains. Further, complementary research is reported in this study. Firstly, the possibility of using SLS solutions to control surface mould development and bluestain was investigated. Results showed that SLS did control the development of blue stain and mould growth in open-stacked boards for up to three weeks, using concentrations as low as 0.1%, and up to two weeks in closed-stacked timber when using concentrations of 0.2%. Secondly, it was investigated whether SLS treatment would have a detrimental effect on downstream product quality; in particular, kiln dried boards and glued components for furniture manufacturing. Since SLS influenced fluid water flow during kiln drying, the treatment could have exacerbated the occurrence of surface checking due to altered moisture distribution profiles. Results of this investigation showed that the SLS treatment did not result in increased surface checking. Thirdly, as furniture quality timber treated with SLS would be glued, (and also finished with surface coatings), it was further considered important to determine if SLS treatment influenced adhesion properties of wood surfaces. Based on shear test results, it was established that SLS did not influence the adhesion properties of wood when glued with two most commonly used glues in the furniture industry i.e. polyvinyl acetate (PVAc) and urea formaldehyde (UF).

Thesis (MSc)--Stellenbosch University, 2005. / No english abstract available. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die effek van warm water uitloging van houtspaanders by hoë temperature en onder hoë druk voor alkaliese verpulping te ondersoek. Warm water uitloging van houtspaanders onder druk voor alkaliese verpulping was baie belowend, aangesien dit ekstrakstowwe verwyder het wat andersins verteringschemikalieë sou opgebruik het en ook verbertede verpulpingstoestande meegebring het. Gedurende uitloging het die houtstruktuur verander agv die verwydering van die ekstrakstowwe. Dit het veroorsaak dat die houtstruktuur meer toeganglik geword het, en dit het gelei tot 'n verbeterde diffusie van die kookloog. Die versnelde kookloogdiffusie het 'n verbeterde en meer gelykmatige delignifikasie meegebring. Warm water uitloging by verhoogde druk is ondersoek vir drie houtsoorte nl. Eucalyptus grandis, Acacia mearnsii en Pinus patuia. 'n Twee-uur en 'n een-uur uitlogingstyd van die houtspaanders voorafgaande Kraft en soda-AQ verpulping is ondersoek.Vergelyk met 'n een-uur uitloging is daar gevind dat die twee-uur uitloging van die houtspaanders te drasties was, met 'n gevolg van 'n vermindering in pulpopbrengs, vesellengte en pulpsterkte. Die verlaging III pulpsterkte kon toegeskryf word aan polisaggariedafbreking. Die een-uur uitloging het 'n hoër opbrengs opgelewer as beide die kontrole (nie uitgeloogde houspaanders) en die twee-uur uitgeloogde houtspaanders. Die een-uur uitlogingsperiode het besonder goeie verpulpingsresultate vir die ekstrakstofryke Acacia mearnsii houtspaanders getoon, met 'n bykomstige verbetering in pulpsterkte eienskappe.

Comparisons were made between the sensitivities of unique ‘wild’ isolates and domestic isolates of the dry rot fungus, <i>Serpula lacrymans</i>, to temperature, water potential and pH. Comparisons were also made between their capacities of timber decay. The ‘wild’ Himalayan isolates displayed slightly less marked sensitivities to high and low temperature and lowered water potential, yet the isolates were equally tolerant of pH. In general, the linear growth rates of the domestic isolates proved to be twice those of the ‘wild’ Himalayan set, whereas little variation occurred between their rates of timber decay. This study also resulted in the first isolation and reliable identification of ‘wild-growing’ <i>S. lacrymans</i> collected in Europe. The main part of the project involved the construction of novel chambers in order to examine the effects of lowered humidity and moving air flow on the activity of <i>S. lacrymans</i>. In the smallest and simplest of these, its growth and timberdecaying activities could be stopped by incubation at 86% relative humidity or by the application of a pumped air flow rate of 2.5 litres per minute; however, <i>S. lacrymans</i> was not inactivated until more-stressful conditions were applied. In addition, an intermediate rate of air flow provoked marked directional growth away from the stress. Furthermore, the introduction of stone, brick and plaster into these models encouraged the capacities of timber decay and mycelial growth. The use of a larger and more representative model incorporating simulated flooring and plaster walling within glass tanks revealed differences in the appearances and patterns of colonisation by <i>S. lacrymans</i> depending upon whether aged or new materials were used. Treatments involving air drying by fans caused both a shrivelling and a loss of viability of the fungus only when there was no ‘reservoir’ of water available; when there was water present, latent activity remained. An elaboration of this experimental design tested the effects of a combined biological and environmental treatment. Subsequently, the application of <i>Trichoderma harzianum</i>, a known antagonist of <i>S. lacrymans</i>, proved not to be an effective remedial treatment on its own, but appeared to impart a mildly protective effect when combined with a drying regime. Importantly, in the latter situation <i>T. harzianum</i> caused a severe degradation of the part of the colony responsible for the uptake of water in <i>S. lacrymans</i>. Another workshop-scale model simulating more authentically a damp sub-floor space and a cavity behind aged plaster walling was developed. When respective treatments by fan drying and passive ventilation were compared, the former were more effective, but its efficacy could be augmented by incorporating low-level passive ventilation via discreet vents. In this manner, a successful remedial treatment of <i>S. lacrymans</i> could be effected, though the prevalence of mould could prove to be undesirable in practice. However, some samples of this displayed antagonistic effects against <i>S. lacrymans</i>. A further experiment was designed to test the effects of air drying on the production of the stress-protective carbohydrate trehalose and of some associated solutes by <i>S. lacrymans</i>. In contrast to reports of some other organisms, no definite stockpiling of any of the compounds occurred. A final series of experiments revealed that <i>S. lacrymans</i> removed calcium, silicon and iron from sandstone and calcium, sulphur and iron from aged plaster; these elements were sequestered on its hyphae, especially in the form of calcium oxalate. Degradation of the sandstone was implicit but not obvious microscopically. Furthermore, <i>S. lacrymans</i> transported iron from these building materials through its mycelial system. An attempt to determine the effects of separate minerals in sandstone and plaster on timber decay revealed few variations.

Thesis (M.A.)--Boston University / The question --- whether a biological concept, such as evolution, can have a profound effect in such a remote field of study as professional philosophy --- must begin with a discussion of what evolution means to biologists, and did mean at the time the philosopher in question was formulating his philosophy. The names of Lamarck, Darwin, and DeVries stand for three theories of the method of evolution, current at the time Sellars was formulating his metaphysics; and there was no acceptable way of choosing among them. However, all were agreed that evolution had occurred and by evolution they meant a continuous chain of descent accompanied by modification of inheritance until new species had been formed. Since Sellars does, as most philosophers do, have his own vocabulary of special terms, the need of a glossary is indicated, to contain terms as: thing, existent, datum, content, perception, category, thinghood, intuit, knowledge, object, correspond, physical, law, connection, continuity, structure, function, organism, system, emergence, time, explanation, history, and cumulation. The thorough explanation of these terms acts to describe, to a considerable extent, Sellars' philosophy. However, another separate chapter is necessary to give an adequate picture of Sellars' metaphysics, epistemology, unification of the sciences, approach to the mind-body problem, emphasis on evolution, and rejection of God. [TRUNCATED]

It has long been known that the presence of wood in rivers plays a vital biological and functional role and that a reciprocal relationship exists between woody material and the geomorphology of rivers. Fluvial wood studies, however, are rarely ongoing through time in order to ascertain long-term wood patterns within complete drainage networks. This dissertation addresses the temporal lag in fluvial wood patterns throughout four watersheds in the Oregon Coast Range by recreating a field dataset first collected in 1979 and then again in 1998. Statistical and spatial analysis of stream morphometric data at designated transects throughout the watersheds in addition to analysis of log step and log jam inventories provide insight into significant changes that have occurred over a thirty year interval at a multi-basin scale. These watersheds are located in areas that have been impacted by years of timber harvesting in the mid-twentieth century, however, clearcutting has been on the decline since the early 1980s. This research investigates the impacts that the legacy of clearcutting and subsequent afforestation has had on the abundance and volume of fluvial wood in the stream networks of these four watersheds. I digitized historical aerial imagery to determine the amounts of clearcutting in the basins over time. I integrated this variable with channel morphometric variables to assess predictors of wood abundance and volume through multiple regression analysis. Results show that the stream that has been the most affected by clearcutting has lower volumes of wood than measured in 1979 or 1998. Residence times of wood are short in these watersheds and wood abundance and volume was highly impacted by the debris flows that occurred during the Storm of 1996, prior to the 1998 data collection. There are statistically significant changes that have occurred in the stream morphology among the four watersheds. This dissertation also tests a method of detecting fluvial wood through airborne lidar analysis. This method provides an alternative to field surveys in areas of even the most extreme tree canopy cover.

Kinetic profiles were investigated for the pyridine catalysed reaction of Corsican (CP) and Scots pine (SP) sapwood with a homologous series of linear chain carboxylic anhydrides namely, acetic (AA), propionic (PA), butyric, valeric and hexanoic (HA). With AA. it has been found that the reaction profiles are described by a model where diffusion dominates the reaction process, that is to say that reaction of the reagent molecules with a specific reaction site is rapid compared with diffusion. With longer chain anhydrides, the rate of chemical reaction and diffusion both contributed to the reaction kinetics. The reaction activation energies (Ea) were detennined for the catalysed reaction of pyridine swollen pine sapwood samples and phenolic model compounds (in solution) with the series of anhydrides, using the methods of initial rates and rate constants. Both methods resulted in comparable values. The wood species did not influence the Ea. With wood samples, the Ea was largest for the reaction of AA, and decreased as the molecular weight of the anhydride increased. When the reactions were performed in homogeneous solutions, there was no correlation molecular weight of anhydride and Ea. It is suggested that the lower values obtained for the Ea for reaction with wood are related to the restricted space surrounding the accessible hydroxyl groups (OH). The cell wall micropore network of oven-dried (OD) CP and SP sapwood was investigated by reaction with AA and PA in a non-swelling solvent (xylene) and with swollen wood. Significant differences in reactivity were found between species. The volumetric changes in CP and SP sapwood due to modification with the series of anhydrides were studied. Again significant differences in the response of the wood cell wall were found between species. A comprehensive investigation into the water sorptive properties and into the effect of molecular size of the substituent group upon the sorption of water vapour of softwood modified with the series of anhydrides was perfonned. The sorption isotherms for untreated and chemically modified wood were analysed using the Hailwood-Horrobin model. The results are interpreted by consideration of both the number of OH groups reacted and the volume occupied by adduct in the cell wall. It is considered that the latter effect is more important. In the final part of this study, an approach was made to investigate the cell wall porosity of unmodified and modified wood, using the nitrogen adsorption technique. Results indicated that the true porosity of the cell wall was not determined by this technique.